I'm not sure which camera app or version you are using. Try swiping from either the left or right of the screen to bring up more options. I remember one version of my camera app on my Nexus 5 being that way, but I can't look at it right now.
If I remember correctly, swiping from the right brings up settings and swiping from the left brings up some extra camera controls such as switching front to rear facing, etc.